This invention relates generally to aircraft ejection seats and, more particularly, to a means for stabilizing the yaw of an aircraft ejection seat after it has been ejected.
In the attempt to stabilize aircraft ejection seats, drogue parachutes are often utilized. The drogue chute, however, presents certain disadvantages. First, since it tends to align with the relative windstream, it inhibits stabilization of the seat in the pitch and roll axes. Second, current ejection seats are so unstable that they may begin to tumble and spin before the drogue chute is fully deployed. This results in the drogue chute or its lines being wrapped around the seat or becoming entangled on seat components, creating a situation which could seriously jeopardize the survival of the ejected airman.
Various means, other than drogue chutes have been devised to control the flight of ejection seats. For example, one type of ejection seat has a plurality of inflatable air bags in two vertical rows on the back of the seat. When these bags are inflated they provide stabilization by reducing the aerodynamic drag in the wake region of the seat. However, there may be a substantial time delay after ejection before the air bags are fully deployed. Therefore, significant tumbling and rotation could result before the air bags became effective. Furthermore, this ejection seat does not have any means to prevent entanglement of the main chute in the inflated air bags.
Another type of ejection seat has a pair of fin assemblies which include both horizontal and vertical fins. These fins provide air drag forces after ejection in order to keep the seat from rotating too far backward. They are fully deployed at the time of ejection and move only in response to the main windstream. However, the function of the fins is limited to aligning the seat for minimal drag. Furthermore, there is no means provided for preventing entanglement of the main chute in the fin assemblies.
There are also other types of ejection seats which have deployable rotors and tail fins. However, deployment and deceleration are still initiated by a drogue chute in these ejection seats. Thus the problems are discussed above which surround deployment of the drogue chute itself would still be present in these ejection seats. Furthermore, neither of these ejection seats has parachute anti-entanglement means since they apparently do not utilize parachutes to control descent.